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The specifications of a WiFi module meant for embedded projects, says --

  • mini PCIe format
  • Host interface supports USB.2.0
  • Works with any board with mini PCIe.

Not sure about the interplay of mini PCIe and USB here. Are those 2 options / alternatives for each other ?

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    \$\begingroup\$ Why the downvote ? \$\endgroup\$
    – bdutta74
    Feb 21, 2012 at 9:44
  • \$\begingroup\$ Not sure why a downvote with no comment or vote to close... But this is off topic. Sounds more like a super user question. \$\endgroup\$
    – Kellenjb
    Feb 21, 2012 at 12:26
  • \$\begingroup\$ Thanks @Kellenjb. With due regards to the Mods and Gurus here, but look at the question from the eyes of someone who doesn't have a formal electronics background, is a hobbyist, and is asking a question which is clearly not a shopping question, but specifically about something which can very well be confusing to someone not familiar. PCIe and USB both are interface specifications AFAIK. \$\endgroup\$
    – bdutta74
    Feb 21, 2012 at 14:52
  • \$\begingroup\$ I actually missed the part of your question where you said "meant for embedded projects". I guess that's what I get for reading it from my phone. I thought you were asking about a WiFi module that you were putting into a computer. So, I would take back my close vote if I could. \$\endgroup\$
    – Kellenjb
    Feb 21, 2012 at 15:27

1 Answer 1

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The statement:

  • Host interface supports USB.2.0 Works with any board with mini PCIe.

Means:

  • The card in question physically interfaces via a PCIe "socket".
    One of the connections which can be established over this connector is USB2. The USB data lines are usually on pins 36 & 38 of the connector, BUT they are not present in some implementations and if someone put USB on some other pins in a particular implementation you shopuld not be completely surprisd - BUT, it probably means it uses USB2 on PCI-e pins 36 & 38.

The situation is confused by there being various sub-implementations or semi-non-standard or very non standard implementations. Note that when eg SATA is used the USB pins are "reserved" implying that you MAY in some cases be able totalk to a drive via SATA or USB2.

USB data is usually carried on pins 36 and 38 BUT no absolute guarantees.

This webpage does a fair job of showing standard and some non standard implementations
Clearer version on webpage.

enter image description here

Wikipedia on PCI express says as below, which covers the USB2 part of your query.

  • PCI Express Mini Card edge connector provide multiple connections and buses:

    PCIe ×1
    USB 2.0
    SMBus
    Wires to diagnostics LEDs for wireless network (i.e., Wi-Fi) status on computer's chassis
    SIM card for GSM and WCDMA applications. (UIM signals on spec)
    Future extension for another PCIe lane 1.5 and 3.3 volt power)

A typical PCI-e wireless LAN card whose webpage contains the search string you ask about has the picture below. And includes text

  • Host Interface supports USB 2.0 via mini PCIe format.

and

  • Works with any board equipped with mini PCIe.

"via mini PCIe" and "equipped with mini PCIe" tell you that this is NOT an alternative to USB2.

That pretty much covers the PCI-e aspect of your query.

enter image description here

Many bus pinouts excellent

Including PCI-e

Excellent PCI-e resource page

Gargoyling

  • Host interface supports USB.2.0 Works with any board with mini PCIe.

produces a slew of material with that exact string, and many that answer your questions and various explanatory material as well.

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  • \$\begingroup\$ Thanks @Russell. I can say for sure that your first introductory paragraph clears the thing about 75%, but had to read the rest (thrice) to get the remaining 25%. I am almost certain that just by reading Mini PCI Express Pinouts, article - i.e. without the highlighted text with differences, you've provided, this wouldn't have been clear. \$\endgroup\$
    – bdutta74
    Feb 21, 2012 at 18:28
  • \$\begingroup\$ Oh, and bulls-eye with the specific WiFi module \$\endgroup\$
    – bdutta74
    Feb 21, 2012 at 18:29
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    \$\begingroup\$ where'd "pin 236" slip in from? \$\endgroup\$
    – Ben Voigt
    Feb 22, 2012 at 15:25
  • \$\begingroup\$ Quite likely to be a typo. I'd seen it too, but I assumed it to mean "pin 36". \$\endgroup\$
    – bdutta74
    Feb 23, 2012 at 17:27
  • \$\begingroup\$ @Russell, hope that I am not pushing my luck here... when you wrote... "via mini PCIe" and "equipped with mini PCIe" tell you that this is NOT an alternative to USB2.... does it mean that, just by connecting the standard USB pins, i.e. +5V, GND, D+ and D- to the corresponding pins of this module, I cannot expect the module to function as a standard USB device ? Because, that is what I was intending to ask, and then it'd be the simple task of including the standard Linux drivers for this on my ARM SBC, to use this module. \$\endgroup\$
    – bdutta74
    Feb 23, 2012 at 17:35

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